The Family contains five genera with some thirty-five species, varying in size from fourteen inches in Merops natalensis to about six and half in several forms of Melittophagus. Nyctiornis amictus, of the Malay countries, is green, with lilac forehead and crown, scarlet cheeks and throat-tuft, and a few greenish-blue plumes at the base of the bill. Meropogon forsteri of Celebes is also green, but has the crown, gular plumes and breast cobalt-blue, the occiput and nape brown, the abdomen dusky, and the lateral tail-feathers reddish-brown margined with green. Merops apiaster has ruddy-brown head, neck, upper back, and broad alar bar, buff lower back, green wings and tail with black tips to the long median rectrices, light blue upper tail-coverts, pale green and white forehead, black ear-coverts, and bright yellow throat, divided from the greenish-blue under parts by a black band. It not unfrequently visits Britain–as the Blue-tailed Bee-eater, M. philippinus, is said to have done once–and ranges from South Europe to Central Asia and North Africa, wintering in North-West India and South Africa. M. viridis, extending from Senegambia to North-East Africa and Cochin China, is yellowish-green, with a rufous tint on the hind-neck, much buff on the wing- and tail-quills, a black band washed with blue on the fore-neck, and some blue and black on the face. M. nubicus of the northern half of the Ethiopian Region has crimson-pink upper parts, blue-green head and throat, light blue rump and abdomen, rose-pink breast, black markings on the sides of the head, and black tips to the remiges and rectrices. Melittophagus gularis of West Africa is glossy black above, with bright blue on the forehead, rump, wings and median tail-feathers; the throat is crimson, the lower surface black with blue streaks; the wing-quills are for the most part rufous margined with black.
The Old World Families Bucerotidae and Upupidae are united under the latter appellation by Dr. Gadow,[[227]] who recognises the Sub-families Bucerotinae or Hornbills, Upupinae or Hoopoes, and Irrisorinae or Wood-Hoopoes; but the two aforesaid groups should decidedly be kept separate.
Fam. V. Bucerotidae.–The Hornbills derive their name from the immensely developed bill and casque, or helmet, found in such forms as Buceros (p. [395]), though the excrescence in Aceros and some species of Lophoceros is rudimentary. It may be mentioned that the huge beak of the Toucans denotes no affinity to this group. The casque–open in front in Bucorvus–is more or less filled with cellular bony tissue, or with an almost solid mass of bony columns in Rhinoplax; the mandibles are occasionally serrated. The metatarsi are short, save in the terrestrial Bucorvus, and are rough and scaly; the toes have broad flat soles, the second and third being united for one phalanx, the third and fourth still further. The powerful wings have eleven primaries, and from ten to sixteen secondaries, while the under coverts do not perfectly cover the base of the quills. The tail has ten rectrices and is usually long, though shorter in Bucorvus; it is either square or graduated, and has the two median feathers much elongated in Rhinoplax and Ortholophus. The furcula is U-shaped, the tongue rudimentary; the aftershaft is wanting; there is no down on the adults or callow young; and the eyelashes are prominent, a rare feature among birds. In most forms the atlas (p. [5]) fuses with the axis.
These arboreal birds, termed "Calaos" in French, frequent deep tall jungle or cultivated districts near rivers, up to five thousand feet; most, if not all, of the species descending from the trees in the morning and evening, when they have been observed bathing in streams, and digging up loose soil with their beaks. Bucorvus spends much of the day upon the ground searching for food.
Fig. 82.–Hornbill. Dichoceros bicornis. Female and young. (From Malay Archipelago.)
The flight, often prolonged to considerable distances, is heavy and slow, the unwieldy body acting as a great drag, though counterbalanced by the pneumaticity, or air-containing nature of the bones, which is perhaps greater in Hornbills than in any other birds. On the wing a sound is generally produced like that of a steam-engine, possibly due to the open nature of the quills; but Rhinoplax, Berenicornis, Anorhinus, and Anthracoceros malabaricus are said to fly noiselessly. In some species the wing-action is regular; in others, rapid strokes alternate with sailing movements on outspread pinions; the head is usually drawn in and the tail depressed; while flocks proceed in single file. Individuals alight heavily, and from their bulk are restricted to the stronger branches, along which they shuffle awkwardly, even assisting themselves with their beak.
Hornbills may be met with singly or in pairs, but ordinarily form parties of five or six, if not of larger numbers, gathering together to feed or to roost at fixed spots, which they leave before sunrise. They are not naturally shy, and if disturbed only resort to some neighbouring tree, where they may be often observed sitting on the boughs during the mid-day hours, with puffed out plumage, open bill, and head sunk upon the back as if overcome by the heat. From time to time while perched they elevate or depress the crest and utter loud yelping cries, not uncommonly flapping their wings and bowing their heads; when feeding they constantly chatter in chorus like Parrots, and vanish with shrill screams if intruders appear. The characteristic note, however, is a harsh, continuous sound, intermediate between the bray of an ass and the shriek of a railway engine; that of Bucorvus abyssinicus has been syllabled "hūm-hūm," and that of B. cafer, the "Bromvogel" of South Africa, has been said to resemble a lion's roar, and to be audible for a mile. All the species are apparently most noisy in the morning and evening, or before rain.
Fruits and insects–the latter occasionally hawked for in the air–constitute the normal food, but the larger forms devour small mammals, birds, eggs and reptiles, with grubs, flowers, and young shoots; while Bucorvus, which feeds chiefly upon the ground, and hops rapidly, will eat tortoises, mandioc-roots, and so forth. Berries of Strychnos and figs seem greatly in favour. Nearly everything is swallowed entire, with a backward jerk of the head, animals having the life beaten out of them previously, and most substances being tossed up into the air. The male has a most curious habit of casting up the lining of the gizzard with its contents enclosed, possibly to feed the female or young.[[228]]
A hole in a tree or a cavity at the junction of two branches serves for the nest, wherein the hen is enclosed by a plaster of dung or like material; there, under penalty of death, she remains until she emerges dirty, wasted and enfeebled, when the brood is hatched. From one to four dingy white eggs with coarse pores are deposited upon the débris or a few feathers. Contrary to expectation, observations seem to shew that the female walls herself in; but, however that may be, the cock feeds her through the small opening left, and is even said to knock with his bill to attract her attention as he clings to the bark. He shews great anxiety about his charge, and the hen screams and bites if molested. Various members of the Family expand the tail and inflate the throat when courting; some thrive fairly well as pets; while Aceros nipalensis of India, and Dichoceros bicornis, the Homrai, ranging thence to the Malay countries, are said to be excellent eating. The latter is sacred to Vishnu; the immured female of Rhytidoceros subruficollis serves as a type of virtue to the Burmese; and natives believe that the plaster for the holes is composed of gum and earth from the four quarters of the globe. In South Africa the Fingoes think that their cattle will contract disease if Hornbills are shot; Kafirs consider that drought will cease if one of them is sunk under water and drowned; Ovampos pretend that the eggs are too brittle to be handled.